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Graphical Grimsley

by Dave Studeman
June 09, 2006

It's the latest baseball scandal—Jason Grimsley took steroids, he took greenies, he took Human Growth Hormone. Once diligent steroid testing began (and after he tested positive for steroids in 2003), he quit the 'roids. But he kept taking HGH, and he's not the only one. Now that he's been caught, he's naming names.

I know it sounds terrible, but I take some pleasure in this latest news. Hasn't it been obvious that lots of players beside Barry Bonds have taken illegal drugs for years to enhance their performance? Can't we now spread our ire to the many instead of the few?

This is obviously just the beginning of the next black mark for baseball. In the meantime, I've been wondering if we could pick out when, exactly, Grimsley started using the stuff. According to the affidavit, he first took steroids in 2000 to help him recover from Tommy John surgery, but he may have been taking them sooner. Can we pinpoint a date? Did the drugs have an impact? Let's see. First, here's a graph of Grimsley's ERA for every year of his career...

Whoa. Tom Verducci claims that Jason Grimsley was a different pitcher in 1999 and it sure looks like something happened between 1996 and 1999, doesn't it? Of course, maybe he just got better, or maybe he performed better in relief (he was primarily a starter before 1999 and a reliever afterwards) Let's take a closer look at some of his component stats. First, strikeouts per nine innings...

If steroids impact strikeout rates, it doesn't appear that Grimsley's medical routine had an impact until 2001 and 2002. And even then the evidence is sketchy. How about walks per nine innings?

This is surprising. It appears that Grimsley's drug routine may have helped him locate the ball better. I'm sure the truth isn't that simple, but this kind of finding is perplexing. How about home run rates, you ask?

Some evidence, but nothing too compelling here. Steroids and HGH might have helped Grimsley keep the ball in the park but, as a groundball pitcher, he didn't give up a lot to begin with. For one last clue, let's take a look at his Batting Average on Balls in Play (or BABIP):

This is, perhaps, most telling. Grimsley's batted balls were fielded more often, for whatever reason, after 1998. As a groundball pitcher, Grimsley's BABIP would tend to be above the average, but perhaps he gained an extra measure of movement or speed on his sinker, making his balls more fieldable and giving him more confidence to throw strikes.

This is all speculation, of course. Drugs may have had no impact on Grimsley's performance at all. Perhaps he was just better suited to a relief role. If drugs did make an impact, it seems that he started taking them before 2000.

Uncovering the impact of performance-enhancing drugs for any single player is not going to be easy.

Addendum: I just looked up Jason Grimsley in Bill James/Rob Neyer's Guide to Pitchers and found two different Scouting Notebook pitch selection notes:

1995: 1. Fastball (86-88) 2. Slider 3. Split-Fingered Fastball
2001/2003: 1. Fastball (mid-90's) 2. Sinker 3. Split-Fingered Fastball (occasional)

Rob Neyer also noted that Grimsley's primary pitch in 2002/2003 was a sinker in the low 90's. It would appear the speed gun is a much better indicator of which pitchers have taken steroids/HGH (and when) than strikeout rates.

References and Resources
All graphs are courtesy of Fangraphs, a tremendous resource for Internet baseball fans everywhere.

Dave is the manager of the Baseball Graphs website.. Comments about this article can be sent to him through the miracle of e-mail.

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